Lights used by photographers in their studios are typically designed for high light output without regard for their bulk and weight. The associated supported equipment is sized to match. Since such support equipment is not readily portable, it is transported to and from the studio only at considerable effort and expense when a photographer is called on to set up complex lighting on location.
Non-studio freelance photographers do most of their work utilizing natural or available light. Their limited physical resources restrict them to minimal and simple lighting--often lightweight battery-powered stroboscopic (strobe) lights.
Boom lighting equipment is an item of support equipment hat is rarely available to either type of photographer by virtue of its massive structure and weight. Historically, common wisdom has dictated that photographic boomstands be structured in the style of a derrick with its boom supported in cantilever fashion, necessitating rigid, bulky, and heavy members even though modern strobes are readily available which separate the relatively lightweight light/reflector assembly from the heavy power pack.
An important aspect of this invention therefore lies in the recognition that support apparatus, particularly of the type used in connection with lighting equipment for photographic purposes, need not be rigid and that a flexible boom and/or a standard, if properly constructed and balanced, may be highly effective for such purposes. With flexibility being a permissible specification, the cross sectional dimensions and wall thickness of the parts may be greatly reduced and, with other requirements met, the result is a compact, lightweight assembly that is highly portable and may be easily assembled and adjusted by a photographer without help from others.
A further aspect of this invention lies in the recognition that these objectives may be in part achieved by providing a stand that utilizes a sling suspension for the equipment-supporting boom. The boom is a "floating" one in a sense that is not directly connected to the vertical support standard. Instead, it is carried by a suspension cable that has its intermediate portion adjustably secured to a retainer at the top of the standard and has its ends adjustably connected to opposite end portions of the boom. Positioning of the cable with respect to the retainer and to its points of connection with the boom are fully adjustable to achieve a balanced condition under various loadings and angular orientations of the boom. Although the lightweight boom has considerable flexibility, proper adjustment of the suspension cable causes the boom to assume a rectilinear condition with the result that load forces are applied to the boom and standard as axial compressive forces rather than flexing or distorting forces.
The invention also includes the provision of dependable, highly-effective means for adjustably securing the suspension cable to both the boom and the standard and for reliably holding the telescoping sections of the standard in whatever degree of extension is selected. Such means takes the form of collars having bores that are relieved by arcuate recesses which define pairs of circumferentially-spaced contact edges along the longitudinal lines of merger between the surfaces of the recesses and the cylindrical (or partially-cylindrical) surfaces of the bores. A thumbscrew or set screw is provided by each collar, such screw facing generally in the direction of such contact edges and extending along a plane equidistant therebetween. Tightening of the thumbscrew against a cylindrical member extending through the collar forces that member into tight, non-slipping engagement with the spaced contact edges. Despite the high unit gripping force achieved by such an arrangement, the thumbscrews may be easily turned to permit disengagement or readjustment of the parts whenever desired.
The retainer at the top of the vertical standard preferably takes the form of a transverse member having at least one arcuate, upwardly-facing groove defined by a pair of spaced bearing surfaces. Ideally, the member is generally cylindrical and the groove extends circumferentially with its axis perpendicular to that of the standard. The groove tapers inwardly from a width greater than that of the cable to a width less than the cable's diameter. The weight of the boom and its load securely holds the cable in a selected position of adjustment within the groove; however, release of the cable from the retainer may be easily achieved simply by lifting it from the groove.
Other features, objects, and advantages of the invention will become apparent from the specification and drawings.